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postgresql/src/backend/executor/nodeSubplan.c

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/*-------------------------------------------------------------------------
*
* nodeSubplan.c
* routines to support subselects
*
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/nodeSubplan.c,v 1.86 2007/02/22 22:00:23 tgl Exp $
*
*-------------------------------------------------------------------------
*/
/*
* INTERFACE ROUTINES
* ExecSubPlan - process a subselect
* ExecInitSubPlan - initialize a subselect
* ExecEndSubPlan - shut down a subselect
*/
#include "postgres.h"
#include <math.h>
#include "access/heapam.h"
#include "executor/executor.h"
#include "executor/nodeSubplan.h"
#include "nodes/makefuncs.h"
#include "optimizer/clauses.h"
#include "utils/array.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
static Datum ExecHashSubPlan(SubPlanState *node,
ExprContext *econtext,
bool *isNull);
static Datum ExecScanSubPlan(SubPlanState *node,
ExprContext *econtext,
bool *isNull);
static void buildSubPlanHash(SubPlanState *node);
static bool findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot);
static bool slotAllNulls(TupleTableSlot *slot);
static bool slotNoNulls(TupleTableSlot *slot);
/* ----------------------------------------------------------------
* ExecSubPlan
* ----------------------------------------------------------------
*/
Datum
ExecSubPlan(SubPlanState *node,
ExprContext *econtext,
bool *isNull,
ExprDoneCond *isDone)
{
SubPlan *subplan = (SubPlan *) node->xprstate.expr;
/* Set default values for result flags: non-null, not a set result */
*isNull = false;
if (isDone)
*isDone = ExprSingleResult;
if (subplan->setParam != NIL)
elog(ERROR, "cannot set parent params from subquery");
if (subplan->useHashTable)
return ExecHashSubPlan(node, econtext, isNull);
else
return ExecScanSubPlan(node, econtext, isNull);
}
/*
* ExecHashSubPlan: store subselect result in an in-memory hash table
*/
static Datum
ExecHashSubPlan(SubPlanState *node,
ExprContext *econtext,
bool *isNull)
{
SubPlan *subplan = (SubPlan *) node->xprstate.expr;
PlanState *planstate = node->planstate;
ExprContext *innerecontext = node->innerecontext;
TupleTableSlot *slot;
/* Shouldn't have any direct correlation Vars */
if (subplan->parParam != NIL || node->args != NIL)
elog(ERROR, "hashed subplan with direct correlation not supported");
/*
* If first time through or we need to rescan the subplan, build the hash
* table.
*/
if (node->hashtable == NULL || planstate->chgParam != NULL)
buildSubPlanHash(node);
/*
* The result for an empty subplan is always FALSE; no need to evaluate
* lefthand side.
*/
*isNull = false;
if (!node->havehashrows && !node->havenullrows)
return BoolGetDatum(false);
/*
* Evaluate lefthand expressions and form a projection tuple. First we
* have to set the econtext to use (hack alert!).
*/
node->projLeft->pi_exprContext = econtext;
slot = ExecProject(node->projLeft, NULL);
/*
* Note: because we are typically called in a per-tuple context, we have
* to explicitly clear the projected tuple before returning. Otherwise,
* we'll have a double-free situation: the per-tuple context will probably
* be reset before we're called again, and then the tuple slot will think
* it still needs to free the tuple.
*/
/*
* Since the hashtable routines will use innerecontext's per-tuple memory
* as working memory, be sure to reset it for each tuple.
*/
ResetExprContext(innerecontext);
/*
* If the LHS is all non-null, probe for an exact match in the main hash
* table. If we find one, the result is TRUE. Otherwise, scan the
* partly-null table to see if there are any rows that aren't provably
* unequal to the LHS; if so, the result is UNKNOWN. (We skip that part
* if we don't care about UNKNOWN.) Otherwise, the result is FALSE.
*
* Note: the reason we can avoid a full scan of the main hash table is
* that the combining operators are assumed never to yield NULL when both
* inputs are non-null. If they were to do so, we might need to produce
* UNKNOWN instead of FALSE because of an UNKNOWN result in comparing the
* LHS to some main-table entry --- which is a comparison we will not even
* make, unless there's a chance match of hash keys.
*/
if (slotNoNulls(slot))
{
if (node->havehashrows &&
FindTupleHashEntry(node->hashtable,
slot,
node->cur_eq_funcs,
node->lhs_hash_funcs) != NULL)
{
ExecClearTuple(slot);
return BoolGetDatum(true);
}
if (node->havenullrows &&
findPartialMatch(node->hashnulls, slot))
{
ExecClearTuple(slot);
*isNull = true;
return BoolGetDatum(false);
}
ExecClearTuple(slot);
return BoolGetDatum(false);
}
/*
* When the LHS is partly or wholly NULL, we can never return TRUE. If we
* don't care about UNKNOWN, just return FALSE. Otherwise, if the LHS is
* wholly NULL, immediately return UNKNOWN. (Since the combining
* operators are strict, the result could only be FALSE if the sub-select
* were empty, but we already handled that case.) Otherwise, we must scan
* both the main and partly-null tables to see if there are any rows that
* aren't provably unequal to the LHS; if so, the result is UNKNOWN.
* Otherwise, the result is FALSE.
*/
if (node->hashnulls == NULL)
{
ExecClearTuple(slot);
return BoolGetDatum(false);
}
if (slotAllNulls(slot))
{
ExecClearTuple(slot);
*isNull = true;
return BoolGetDatum(false);
}
/* Scan partly-null table first, since more likely to get a match */
if (node->havenullrows &&
findPartialMatch(node->hashnulls, slot))
{
ExecClearTuple(slot);
*isNull = true;
return BoolGetDatum(false);
}
if (node->havehashrows &&
findPartialMatch(node->hashtable, slot))
{
ExecClearTuple(slot);
*isNull = true;
return BoolGetDatum(false);
}
ExecClearTuple(slot);
return BoolGetDatum(false);
}
/*
* ExecScanSubPlan: default case where we have to rescan subplan each time
*/
static Datum
ExecScanSubPlan(SubPlanState *node,
ExprContext *econtext,
bool *isNull)
{
SubPlan *subplan = (SubPlan *) node->xprstate.expr;
PlanState *planstate = node->planstate;
SubLinkType subLinkType = subplan->subLinkType;
MemoryContext oldcontext;
TupleTableSlot *slot;
Datum result;
bool found = false; /* TRUE if got at least one subplan tuple */
ListCell *pvar;
ListCell *l;
ArrayBuildState *astate = NULL;
/*
* We are probably in a short-lived expression-evaluation context. Switch
* to the child plan's per-query context for manipulating its chgParam,
* calling ExecProcNode on it, etc.
*/
oldcontext = MemoryContextSwitchTo(node->sub_estate->es_query_cxt);
/*
* Set Params of this plan from parent plan correlation values. (Any
* calculation we have to do is done in the parent econtext, since the
* Param values don't need to have per-query lifetime.)
*/
Assert(list_length(subplan->parParam) == list_length(node->args));
forboth(l, subplan->parParam, pvar, node->args)
{
int paramid = lfirst_int(l);
ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
prm->value = ExecEvalExprSwitchContext((ExprState *) lfirst(pvar),
econtext,
&(prm->isnull),
NULL);
planstate->chgParam = bms_add_member(planstate->chgParam, paramid);
}
ExecReScan(planstate, NULL);
/*
* For all sublink types except EXPR_SUBLINK and ARRAY_SUBLINK, the result
* is boolean as are the results of the combining operators. We combine
* results across tuples (if the subplan produces more than one) using OR
* semantics for ANY_SUBLINK or AND semantics for ALL_SUBLINK.
* (ROWCOMPARE_SUBLINK doesn't allow multiple tuples from the subplan.)
* NULL results from the combining operators are handled according to the
* usual SQL semantics for OR and AND. The result for no input tuples is
* FALSE for ANY_SUBLINK, TRUE for ALL_SUBLINK, NULL for
* ROWCOMPARE_SUBLINK.
*
* For EXPR_SUBLINK we require the subplan to produce no more than one
* tuple, else an error is raised. For ARRAY_SUBLINK we allow the subplan
* to produce more than one tuple. In either case, if zero tuples are
* produced, we return NULL. Assuming we get a tuple, we just use its
* first column (there can be only one non-junk column in this case).
*/
result = BoolGetDatum(subLinkType == ALL_SUBLINK);
*isNull = false;
for (slot = ExecProcNode(planstate);
!TupIsNull(slot);
slot = ExecProcNode(planstate))
{
TupleDesc tdesc = slot->tts_tupleDescriptor;
Datum rowresult;
bool rownull;
int col;
ListCell *plst;
if (subLinkType == EXISTS_SUBLINK)
{
found = true;
result = BoolGetDatum(true);
break;
}
if (subLinkType == EXPR_SUBLINK)
{
/* cannot allow multiple input tuples for EXPR sublink */
if (found)
ereport(ERROR,
(errcode(ERRCODE_CARDINALITY_VIOLATION),
errmsg("more than one row returned by a subquery used as an expression")));
found = true;
/*
* We need to copy the subplan's tuple in case the result is of
* pass-by-ref type --- our return value will point into this
* copied tuple! Can't use the subplan's instance of the tuple
* since it won't still be valid after next ExecProcNode() call.
* node->curTuple keeps track of the copied tuple for eventual
* freeing.
*/
MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
if (node->curTuple)
heap_freetuple(node->curTuple);
node->curTuple = ExecCopySlotTuple(slot);
MemoryContextSwitchTo(node->sub_estate->es_query_cxt);
result = heap_getattr(node->curTuple, 1, tdesc, isNull);
/* keep scanning subplan to make sure there's only one tuple */
continue;
}
if (subLinkType == ARRAY_SUBLINK)
{
Datum dvalue;
bool disnull;
found = true;
/* stash away current value */
dvalue = slot_getattr(slot, 1, &disnull);
astate = accumArrayResult(astate, dvalue, disnull,
tdesc->attrs[0]->atttypid,
oldcontext);
/* keep scanning subplan to collect all values */
continue;
}
/* cannot allow multiple input tuples for ROWCOMPARE sublink either */
if (subLinkType == ROWCOMPARE_SUBLINK && found)
ereport(ERROR,
(errcode(ERRCODE_CARDINALITY_VIOLATION),
errmsg("more than one row returned by a subquery used as an expression")));
found = true;
/*
* For ALL, ANY, and ROWCOMPARE sublinks, load up the Params
* representing the columns of the sub-select, and then evaluate the
* combining expression.
*/
col = 1;
foreach(plst, subplan->paramIds)
{
int paramid = lfirst_int(plst);
ParamExecData *prmdata;
prmdata = &(econtext->ecxt_param_exec_vals[paramid]);
Assert(prmdata->execPlan == NULL);
prmdata->value = slot_getattr(slot, col, &(prmdata->isnull));
col++;
}
rowresult = ExecEvalExprSwitchContext(node->testexpr, econtext,
&rownull, NULL);
if (subLinkType == ANY_SUBLINK)
{
/* combine across rows per OR semantics */
if (rownull)
*isNull = true;
else if (DatumGetBool(rowresult))
{
result = BoolGetDatum(true);
*isNull = false;
break; /* needn't look at any more rows */
}
}
else if (subLinkType == ALL_SUBLINK)
{
/* combine across rows per AND semantics */
if (rownull)
*isNull = true;
else if (!DatumGetBool(rowresult))
{
result = BoolGetDatum(false);
*isNull = false;
break; /* needn't look at any more rows */
}
}
else
{
/* must be ROWCOMPARE_SUBLINK */
result = rowresult;
*isNull = rownull;
}
}
if (!found)
{
/*
* deal with empty subplan result. result/isNull were previously
* initialized correctly for all sublink types except EXPR, ARRAY, and
* ROWCOMPARE; for those, return NULL.
*/
if (subLinkType == EXPR_SUBLINK ||
subLinkType == ARRAY_SUBLINK ||
subLinkType == ROWCOMPARE_SUBLINK)
{
result = (Datum) 0;
*isNull = true;
}
}
else if (subLinkType == ARRAY_SUBLINK)
{
Assert(astate != NULL);
/* We return the result in the caller's context */
result = makeArrayResult(astate, oldcontext);
}
MemoryContextSwitchTo(oldcontext);
return result;
}
/*
* buildSubPlanHash: load hash table by scanning subplan output.
*/
static void
buildSubPlanHash(SubPlanState *node)
{
SubPlan *subplan = (SubPlan *) node->xprstate.expr;
PlanState *planstate = node->planstate;
int ncols = list_length(subplan->paramIds);
ExprContext *innerecontext = node->innerecontext;
MemoryContext tempcxt = innerecontext->ecxt_per_tuple_memory;
MemoryContext oldcontext;
int nbuckets;
TupleTableSlot *slot;
Assert(subplan->subLinkType == ANY_SUBLINK);
/*
* If we already had any hash tables, destroy 'em; then create empty hash
* table(s).
*
* If we need to distinguish accurately between FALSE and UNKNOWN (i.e.,
* NULL) results of the IN operation, then we have to store subplan output
* rows that are partly or wholly NULL. We store such rows in a separate
* hash table that we expect will be much smaller than the main table. (We
* can use hashing to eliminate partly-null rows that are not distinct. We
* keep them separate to minimize the cost of the inevitable full-table
* searches; see findPartialMatch.)
*
* If it's not necessary to distinguish FALSE and UNKNOWN, then we don't
* need to store subplan output rows that contain NULL.
*/
MemoryContextReset(node->tablecxt);
node->hashtable = NULL;
node->hashnulls = NULL;
node->havehashrows = false;
node->havenullrows = false;
nbuckets = (int) ceil(planstate->plan->plan_rows);
if (nbuckets < 1)
nbuckets = 1;
node->hashtable = BuildTupleHashTable(ncols,
node->keyColIdx,
node->tab_eq_funcs,
node->tab_hash_funcs,
nbuckets,
sizeof(TupleHashEntryData),
node->tablecxt,
tempcxt);
if (!subplan->unknownEqFalse)
{
if (ncols == 1)
nbuckets = 1; /* there can only be one entry */
else
{
nbuckets /= 16;
if (nbuckets < 1)
nbuckets = 1;
}
node->hashnulls = BuildTupleHashTable(ncols,
node->keyColIdx,
node->tab_eq_funcs,
node->tab_hash_funcs,
nbuckets,
sizeof(TupleHashEntryData),
node->tablecxt,
tempcxt);
}
/*
* We are probably in a short-lived expression-evaluation context. Switch
* to the child plan's per-query context for calling ExecProcNode.
*/
oldcontext = MemoryContextSwitchTo(node->sub_estate->es_query_cxt);
/*
* Reset subplan to start.
*/
ExecReScan(planstate, NULL);
/*
* Scan the subplan and load the hash table(s). Note that when there are
* duplicate rows coming out of the sub-select, only one copy is stored.
*/
for (slot = ExecProcNode(planstate);
!TupIsNull(slot);
slot = ExecProcNode(planstate))
{
int col = 1;
ListCell *plst;
bool isnew;
/*
* Load up the Params representing the raw sub-select outputs, then
* form the projection tuple to store in the hashtable.
*/
foreach(plst, subplan->paramIds)
{
int paramid = lfirst_int(plst);
ParamExecData *prmdata;
prmdata = &(innerecontext->ecxt_param_exec_vals[paramid]);
Assert(prmdata->execPlan == NULL);
prmdata->value = slot_getattr(slot, col,
&(prmdata->isnull));
col++;
}
slot = ExecProject(node->projRight, NULL);
/*
* If result contains any nulls, store separately or not at all.
*/
if (slotNoNulls(slot))
{
(void) LookupTupleHashEntry(node->hashtable, slot, &isnew);
node->havehashrows = true;
}
else if (node->hashnulls)
{
(void) LookupTupleHashEntry(node->hashnulls, slot, &isnew);
node->havenullrows = true;
}
/*
* Reset innerecontext after each inner tuple to free any memory used
* in hash computation or comparison routines.
*/
ResetExprContext(innerecontext);
}
/*
* Since the projected tuples are in the sub-query's context and not the
* main context, we'd better clear the tuple slot before there's any
* chance of a reset of the sub-query's context. Else we will have the
* potential for a double free attempt. (XXX possibly no longer needed,
* but can't hurt.)
*/
ExecClearTuple(node->projRight->pi_slot);
MemoryContextSwitchTo(oldcontext);
}
/*
* findPartialMatch: does the hashtable contain an entry that is not
* provably distinct from the tuple?
*
* We have to scan the whole hashtable; we can't usefully use hashkeys
* to guide probing, since we might get partial matches on tuples with
* hashkeys quite unrelated to what we'd get from the given tuple.
*/
static bool
findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot)
{
int numCols = hashtable->numCols;
AttrNumber *keyColIdx = hashtable->keyColIdx;
TupleHashIterator hashiter;
TupleHashEntry entry;
ResetTupleHashIterator(hashtable, &hashiter);
while ((entry = ScanTupleHashTable(&hashiter)) != NULL)
{
ExecStoreMinimalTuple(entry->firstTuple, hashtable->tableslot, false);
if (!execTuplesUnequal(slot, hashtable->tableslot,
numCols, keyColIdx,
hashtable->cur_eq_funcs,
hashtable->tempcxt))
return true;
}
return false;
}
/*
* slotAllNulls: is the slot completely NULL?
*
* This does not test for dropped columns, which is OK because we only
* use it on projected tuples.
*/
static bool
slotAllNulls(TupleTableSlot *slot)
{
int ncols = slot->tts_tupleDescriptor->natts;
int i;
for (i = 1; i <= ncols; i++)
{
if (!slot_attisnull(slot, i))
return false;
}
return true;
}
/*
* slotNoNulls: is the slot entirely not NULL?
*
* This does not test for dropped columns, which is OK because we only
* use it on projected tuples.
*/
static bool
slotNoNulls(TupleTableSlot *slot)
{
int ncols = slot->tts_tupleDescriptor->natts;
int i;
for (i = 1; i <= ncols; i++)
{
if (slot_attisnull(slot, i))
return false;
}
return true;
}
/* ----------------------------------------------------------------
* ExecInitSubPlan
*
* Note: the eflags are those passed to the parent plan node of this
* subplan; they don't directly describe the execution conditions the
* subplan will face.
* ----------------------------------------------------------------
*/
void
ExecInitSubPlan(SubPlanState *node, EState *estate, int eflags)
{
SubPlan *subplan = (SubPlan *) node->xprstate.expr;
Plan *plan = exec_subplan_get_plan(estate->es_plannedstmt, subplan);
EState *sp_estate;
/*
* initialize my state
*/
node->needShutdown = false;
node->curTuple = NULL;
node->projLeft = NULL;
node->projRight = NULL;
node->hashtable = NULL;
node->hashnulls = NULL;
node->tablecxt = NULL;
node->innerecontext = NULL;
node->keyColIdx = NULL;
node->tab_hash_funcs = NULL;
node->tab_eq_funcs = NULL;
node->lhs_hash_funcs = NULL;
node->cur_eq_funcs = NULL;
/*
* create an EState for the subplan
*
* The subquery needs its own EState because it has its own rangetable. It
* shares our Param ID space and es_query_cxt, however. XXX if rangetable
* access were done differently, the subquery could share our EState,
* which would eliminate some thrashing about in this module...
*
* XXX make that happen!
*/
sp_estate = CreateSubExecutorState(estate);
node->sub_estate = sp_estate;
sp_estate->es_range_table = estate->es_range_table;
sp_estate->es_param_list_info = estate->es_param_list_info;
sp_estate->es_param_exec_vals = estate->es_param_exec_vals;
sp_estate->es_tupleTable =
ExecCreateTupleTable(ExecCountSlotsNode(plan) + 10);
sp_estate->es_snapshot = estate->es_snapshot;
sp_estate->es_crosscheck_snapshot = estate->es_crosscheck_snapshot;
sp_estate->es_instrument = estate->es_instrument;
sp_estate->es_plannedstmt = estate->es_plannedstmt;
/*
* Start up the subplan (this is a very cut-down form of InitPlan())
*
* The subplan will never need to do BACKWARD scan or MARK/RESTORE. If it
* is a parameterless subplan (not initplan), we suggest that it be
* prepared to handle REWIND efficiently; otherwise there is no need.
*/
eflags &= EXEC_FLAG_EXPLAIN_ONLY;
if (subplan->parParam == NIL && subplan->setParam == NIL)
eflags |= EXEC_FLAG_REWIND;
node->planstate = ExecInitNode(plan, sp_estate, eflags);
node->needShutdown = true; /* now we need to shutdown the subplan */
/*
* If this plan is un-correlated or undirect correlated one and want to
* set params for parent plan then mark parameters as needing evaluation.
*
* Note that in the case of un-correlated subqueries we don't care about
* setting parent->chgParam here: indices take care about it, for others -
* it doesn't matter...
*/
if (subplan->setParam != NIL)
{
ListCell *lst;
foreach(lst, subplan->setParam)
{
int paramid = lfirst_int(lst);
ParamExecData *prm = &(estate->es_param_exec_vals[paramid]);
prm->execPlan = node;
}
}
/*
* If we are going to hash the subquery output, initialize relevant stuff.
* (We don't create the hashtable until needed, though.)
*/
if (subplan->useHashTable)
{
int ncols,
i;
TupleDesc tupDesc;
TupleTable tupTable;
TupleTableSlot *slot;
List *oplist,
*lefttlist,
*righttlist,
*leftptlist,
*rightptlist;
ListCell *l;
/* We need a memory context to hold the hash table(s) */
node->tablecxt =
AllocSetContextCreate(CurrentMemoryContext,
"Subplan HashTable Context",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
/* and a short-lived exprcontext for function evaluation */
node->innerecontext = CreateExprContext(estate);
/* Silly little array of column numbers 1..n */
ncols = list_length(subplan->paramIds);
node->keyColIdx = (AttrNumber *) palloc(ncols * sizeof(AttrNumber));
for (i = 0; i < ncols; i++)
node->keyColIdx[i] = i + 1;
/*
* We use ExecProject to evaluate the lefthand and righthand
* expression lists and form tuples. (You might think that we could
* use the sub-select's output tuples directly, but that is not the
* case if we had to insert any run-time coercions of the sub-select's
* output datatypes; anyway this avoids storing any resjunk columns
* that might be in the sub-select's output.) Run through the
* combining expressions to build tlists for the lefthand and
* righthand sides. We need both the ExprState list (for ExecProject)
* and the underlying parse Exprs (for ExecTypeFromTL).
*
* We also extract the combining operators themselves to initialize
* the equality and hashing functions for the hash tables.
*/
if (IsA(node->testexpr->expr, OpExpr))
{
/* single combining operator */
oplist = list_make1(node->testexpr);
}
else if (and_clause((Node *) node->testexpr->expr))
{
/* multiple combining operators */
Assert(IsA(node->testexpr, BoolExprState));
oplist = ((BoolExprState *) node->testexpr)->args;
}
else
{
/* shouldn't see anything else in a hashable subplan */
elog(ERROR, "unrecognized testexpr type: %d",
(int) nodeTag(node->testexpr->expr));
oplist = NIL; /* keep compiler quiet */
}
Assert(list_length(oplist) == ncols);
lefttlist = righttlist = NIL;
leftptlist = rightptlist = NIL;
node->tab_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
node->tab_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
node->lhs_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
node->cur_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
i = 1;
foreach(l, oplist)
{
FuncExprState *fstate = (FuncExprState *) lfirst(l);
OpExpr *opexpr = (OpExpr *) fstate->xprstate.expr;
ExprState *exstate;
Expr *expr;
TargetEntry *tle;
GenericExprState *tlestate;
Oid rhs_eq_oper;
Oid left_hashfn;
Oid right_hashfn;
Assert(IsA(fstate, FuncExprState));
Assert(IsA(opexpr, OpExpr));
Assert(list_length(fstate->args) == 2);
/* Process lefthand argument */
exstate = (ExprState *) linitial(fstate->args);
expr = exstate->expr;
tle = makeTargetEntry(expr,
i,
NULL,
false);
tlestate = makeNode(GenericExprState);
tlestate->xprstate.expr = (Expr *) tle;
tlestate->xprstate.evalfunc = NULL;
tlestate->arg = exstate;
lefttlist = lappend(lefttlist, tlestate);
leftptlist = lappend(leftptlist, tle);
/* Process righthand argument */
exstate = (ExprState *) lsecond(fstate->args);
expr = exstate->expr;
tle = makeTargetEntry(expr,
i,
NULL,
false);
tlestate = makeNode(GenericExprState);
tlestate->xprstate.expr = (Expr *) tle;
tlestate->xprstate.evalfunc = NULL;
tlestate->arg = exstate;
righttlist = lappend(righttlist, tlestate);
rightptlist = lappend(rightptlist, tle);
/* Lookup the equality function (potentially cross-type) */
fmgr_info(opexpr->opfuncid, &node->cur_eq_funcs[i - 1]);
node->cur_eq_funcs[i - 1].fn_expr = (Node *) opexpr;
/* Look up the equality function for the RHS type */
if (!get_compatible_hash_operators(opexpr->opno,
NULL, &rhs_eq_oper))
elog(ERROR, "could not find compatible hash operator for operator %u",
opexpr->opno);
fmgr_info(get_opcode(rhs_eq_oper), &node->tab_eq_funcs[i - 1]);
/* Lookup the associated hash functions */
if (!get_op_hash_functions(opexpr->opno,
&left_hashfn, &right_hashfn))
elog(ERROR, "could not find hash function for hash operator %u",
opexpr->opno);
fmgr_info(left_hashfn, &node->lhs_hash_funcs[i - 1]);
fmgr_info(right_hashfn, &node->tab_hash_funcs[i - 1]);
i++;
}
/*
* Create a tupletable to hold these tuples. (Note: we never bother
* to free the tupletable explicitly; that's okay because it will
* never store raw disk tuples that might have associated buffer pins.
* The only resource involved is memory, which will be cleaned up by
* freeing the query context.)
*/
tupTable = ExecCreateTupleTable(2);
/*
* Construct tupdescs, slots and projection nodes for left and right
* sides. The lefthand expressions will be evaluated in the parent
* plan node's exprcontext, which we don't have access to here.
* Fortunately we can just pass NULL for now and fill it in later
* (hack alert!). The righthand expressions will be evaluated in our
* own innerecontext.
*/
tupDesc = ExecTypeFromTL(leftptlist, false);
slot = ExecAllocTableSlot(tupTable);
ExecSetSlotDescriptor(slot, tupDesc);
node->projLeft = ExecBuildProjectionInfo(lefttlist,
NULL,
slot,
NULL);
tupDesc = ExecTypeFromTL(rightptlist, false);
slot = ExecAllocTableSlot(tupTable);
ExecSetSlotDescriptor(slot, tupDesc);
node->projRight = ExecBuildProjectionInfo(righttlist,
node->innerecontext,
slot,
NULL);
}
}
/* ----------------------------------------------------------------
* ExecSetParamPlan
*
* Executes an InitPlan subplan and sets its output parameters.
*
* This is called from ExecEvalParam() when the value of a PARAM_EXEC
* parameter is requested and the param's execPlan field is set (indicating
* that the param has not yet been evaluated). This allows lazy evaluation
* of initplans: we don't run the subplan until/unless we need its output.
* Note that this routine MUST clear the execPlan fields of the plan's
* output parameters after evaluating them!
* ----------------------------------------------------------------
*/
void
ExecSetParamPlan(SubPlanState *node, ExprContext *econtext)
{
SubPlan *subplan = (SubPlan *) node->xprstate.expr;
PlanState *planstate = node->planstate;
SubLinkType subLinkType = subplan->subLinkType;
MemoryContext oldcontext;
TupleTableSlot *slot;
ListCell *l;
bool found = false;
ArrayBuildState *astate = NULL;
/*
* Must switch to child query's per-query memory context.
*/
oldcontext = MemoryContextSwitchTo(node->sub_estate->es_query_cxt);
if (subLinkType == ANY_SUBLINK ||
subLinkType == ALL_SUBLINK)
elog(ERROR, "ANY/ALL subselect unsupported as initplan");
if (planstate->chgParam != NULL)
ExecReScan(planstate, NULL);
for (slot = ExecProcNode(planstate);
!TupIsNull(slot);
slot = ExecProcNode(planstate))
{
TupleDesc tdesc = slot->tts_tupleDescriptor;
int i = 1;
if (subLinkType == EXISTS_SUBLINK)
{
/* There can be only one param... */
int paramid = linitial_int(subplan->setParam);
ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
prm->execPlan = NULL;
prm->value = BoolGetDatum(true);
prm->isnull = false;
found = true;
break;
}
if (subLinkType == ARRAY_SUBLINK)
{
Datum dvalue;
bool disnull;
found = true;
/* stash away current value */
dvalue = slot_getattr(slot, 1, &disnull);
astate = accumArrayResult(astate, dvalue, disnull,
tdesc->attrs[0]->atttypid,
oldcontext);
/* keep scanning subplan to collect all values */
continue;
}
if (found &&
(subLinkType == EXPR_SUBLINK ||
subLinkType == ROWCOMPARE_SUBLINK))
ereport(ERROR,
(errcode(ERRCODE_CARDINALITY_VIOLATION),
errmsg("more than one row returned by a subquery used as an expression")));
found = true;
/*
* We need to copy the subplan's tuple into our own context, in case
* any of the params are pass-by-ref type --- the pointers stored in
* the param structs will point at this copied tuple! node->curTuple
* keeps track of the copied tuple for eventual freeing.
*/
MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
if (node->curTuple)
heap_freetuple(node->curTuple);
node->curTuple = ExecCopySlotTuple(slot);
MemoryContextSwitchTo(node->sub_estate->es_query_cxt);
/*
* Now set all the setParam params from the columns of the tuple
*/
foreach(l, subplan->setParam)
{
int paramid = lfirst_int(l);
ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
prm->execPlan = NULL;
prm->value = heap_getattr(node->curTuple, i, tdesc,
&(prm->isnull));
i++;
}
}
if (!found)
{
if (subLinkType == EXISTS_SUBLINK)
{
/* There can be only one param... */
int paramid = linitial_int(subplan->setParam);
ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
prm->execPlan = NULL;
prm->value = BoolGetDatum(false);
prm->isnull = false;
}
else
{
foreach(l, subplan->setParam)
{
int paramid = lfirst_int(l);
ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
prm->execPlan = NULL;
prm->value = (Datum) 0;
prm->isnull = true;
}
}
}
else if (subLinkType == ARRAY_SUBLINK)
{
/* There can be only one param... */
int paramid = linitial_int(subplan->setParam);
ParamExecData *prm = &(econtext->ecxt_param_exec_vals[paramid]);
Assert(astate != NULL);
prm->execPlan = NULL;
/* We build the result in query context so it won't disappear */
prm->value = makeArrayResult(astate, econtext->ecxt_per_query_memory);
prm->isnull = false;
}
MemoryContextSwitchTo(oldcontext);
}
/* ----------------------------------------------------------------
* ExecEndSubPlan
* ----------------------------------------------------------------
*/
void
ExecEndSubPlan(SubPlanState *node)
{
if (node->needShutdown)
{
ExecEndPlan(node->planstate, node->sub_estate);
FreeExecutorState(node->sub_estate);
node->sub_estate = NULL;
node->planstate = NULL;
node->needShutdown = false;
}
}
/*
* Mark an initplan as needing recalculation
*/
void
ExecReScanSetParamPlan(SubPlanState *node, PlanState *parent)
{
PlanState *planstate = node->planstate;
SubPlan *subplan = (SubPlan *) node->xprstate.expr;
EState *estate = parent->state;
ListCell *l;
/* sanity checks */
if (subplan->parParam != NIL)
elog(ERROR, "direct correlated subquery unsupported as initplan");
if (subplan->setParam == NIL)
elog(ERROR, "setParam list of initplan is empty");
if (bms_is_empty(planstate->plan->extParam))
elog(ERROR, "extParam set of initplan is empty");
/*
* Don't actually re-scan: ExecSetParamPlan does it if needed.
*/
/*
* Mark this subplan's output parameters as needing recalculation
*/
foreach(l, subplan->setParam)
{
int paramid = lfirst_int(l);
ParamExecData *prm = &(estate->es_param_exec_vals[paramid]);
prm->execPlan = node;
parent->chgParam = bms_add_member(parent->chgParam, paramid);
}
}
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